Strain gauge sensor accelerometer with improved accuracy

Abstract

An MEMS or NEMS accelerometer adapted to measure an acceleration along a sensing axis includes a substrate featuring a plane; a mass having a central zone and suspended relative to the substrate; a single lever arm comprising: a first end connected to the substrate by means of a first connection adapted to allow rotation of the lever arm about a rotation axis perpendicular to the sensing axis, and a second end connected to the mass by means of a second connection adapted to transmit movement in translation of the mass to the lever arm whilst allowing rotation of the lever arm about the rotation axis; the second end of the lever arm being disposed at the level of the central zone of the mass; at least one strain gauge comprising: a first end connected to the substrate, and a second end connected to the lever arm.

The invention claimed is: 
     
       1. An MEMS or NEMS accelerometer adapted to measure an acceleration along a sensing axis comprising:
 a substrate featuring a plane; 
 a mass having a central zone and suspended relative to the substrate; 
 a single lever arm forming a mass force amplification structure, comprising:
 a first end connected to the substrate by means of a first connection adapted to allow rotation of the lever arm about a rotation axis perpendicular to the sensing axis, and 
 a second end connected to the mass by means of a second connection adapted to transmit a movement in translation of the mass to the lever arm whilst allowing rotation of said lever arm about the rotation axis; 
 
 the second end of the lever arm being disposed at a level of the central zone of the mass; 
 further comprising at least one strain gauge, said gauge being connected to the lever arm, each gauge comprising:
 a first end connected to the substrate, and 
 a second end connected to the lever arm, 
 
 the second connection comprising a main coupling blade rigid along the sensing axis and flexible about the rotation axis of the lever arm. 
 
     
     
       2. The accelerometer according to  claim 1 , comprising at least two strain gauges. 
     
     
       3. The accelerometer according to  claim 2 , the two strain gauges being disposed on respective opposite sides of the first end of the lever arm. 
     
     
       4. The accelerometer according to  claim 1 , the mass being suspended relative to the substrate by at least one third connection adapted to allow the translation of said mass along the sensing axis. 
     
     
       5. The accelerometer according to  claim 4 , the at least one third connection comprising a flexible blade along the sensing axis. 
     
     
       6. The accelerometer according to  claim 4 , comprising a plurality of third connections distributed in a balanced manner relative to a centre of gravity of the mass. 
     
     
       7. The accelerometer according to  claim 1 , the mass being suspended relative to the substrate only by the lever arm. 
     
     
       8. The accelerometer according to  claim 1 , the second end of the lever arm being disposed at the level of a centre of gravity of the mass. 
     
     
       9. The accelerometer according to  claim 1 , the second end of the lever arm being offset (d dec ) relative to a centre of gravity of the mass. 
     
     
       10. The accelerometer according to  claim 1 , the sensing axis being in the plane of the substrate. 
     
     
       11. The accelerometer according to  claim 10 , the first end of the lever arm having a tapered shape along the sensing axis. 
     
     
       12. The accelerometer according to  claim 10 , the first connection comprising two non-parallel blades forming a hinge adapted to allow the rotation of the lever arm about the rotation axis perpendicular to the sensing axis. 
     
     
       13. The accelerometer according to  claim 12 , the two blades being mutually perpendicular. 
     
     
       14. The accelerometer according to  claim 1 , the sensing axis being perpendicular to the plane of the substrate. 
     
     
       15. The accelerometer according to  claim 14 , the first connection comprising two colinear blades configured to form the rotation axis of the lever arm. 
     
     
       16. The accelerometer according to  claim 15 , the second connection further comprising at least one secondary coupling blade connected to the main coupling blade and perpendicular to said main coupling blade.